In a closing method, a work piece constituted by a metal pipe material is rotated and a die is pressed against the work piece while the work piece is heated. Thus, the work piece undergoes plastic deformation as it gradually approaches the die.
A closing machine used in the closing operation comprises an outer diameter chuck that grips an outer peripheral surface of the work piece, and a chuck spindle that drives the outer diameter chuck to rotate together with the work piece. The work piece is closed by pressing the die against the work piece while rotating the work piece about an axis that is offset from the die by a predetermined offset amount.
The closing method and closing machine described above are disclosed in JP2002-153930A.
A conventional closing machine comprises a work piece introducing device for introducing a work piece into the outer diameter chuck. The work piece introducing device introduces the work piece into the outer diameter chuck by conveying the work piece in an axial direction via a conveyor or the like.
However, in this conventional work piece introducing device, the work piece is introduced into the outer diameter chuck by conveying the work piece in the axial direction via a conveyor or the like, and it is therefore difficult to improve the positional precision with which the work piece is introduced into the outer diameter chuck.
It is therefore an object of this invention to improve the positional precision with which a work piece is introduced into an outer diameter chuck in a closing method and a closing machine.